My invention relates to scaffolding systems, and more particularly to pump jack pole type scaffolding equipment.
In numerous residential, commercial and industrial applications, it is necessary to erect scaffolding either internally or externally to enable workers to stand at an elevation above a floor or the ground or other supporting surface. If the scaffolding is to be erected adjacent an interior or exterior wall, the scaffolding system may typically comprise a pair of pump jack poles which are spaced apart on the supporting surface and which may be secured to the wall by suitable braces. The pump jacks ride up and down the poles and have support arms which carry the scaffold staging. The workers stand on the staging and operate the pump jacks to raise and lower the staging.
However, if this pump jack pole type scaffolding is to be erected in a free standing manner, for example, in a central region of a room or in an open area or adjacent to a wall without bracing to the wall, the problems of providing a supporting structure for the pump jack poles having sufficient rigidity and stability to ensure the safety of workers on the scaffolding become very difficult to solve.
If it is desired to be able to move such free-standing scaffolding from one location to another within a work area, without dismantling the scaffolding, a mobile supporting structure may be used. However, this not only aggravates the difficulty in providing sufficient rigidity and stability to the pump jack poles, but also introduces further problems of safety. The wheels used to provide mobility may not be locked tightly enough to prevent movement or may accidentally be left unlocked. Workers have also purposefully left the wheels unlocked in order to be able to move the scaffold alongside a wall from one stationary location to another without dismounting from the scaffold, thereby causing accidents. In addition such mobile scaffold supports have not heretofore been able easily to maintain the pump jack poles in essentially vertical positions despite changes in the level and grade of the supporting surface in each new location.